First Measurement of Bose-Einstein Correlations in Proton-Proton Collisions at $\sqrt{s}=0.9$ and 2.36 TeV at the LHC (open access)

First Measurement of Bose-Einstein Correlations in Proton-Proton Collisions at $\sqrt{s}=0.9$ and 2.36 TeV at the LHC

Bose-Einstein correlations have been measured using samples of proton-proton collisions at 0.9 and 2.36 TeV center-of-mass energies, recorded by the CMS experiment at the CERN Large Hadron Collider. The signal is observed in the form of an enhancement of pairs of same-sign charged particles with small relative four-momentum. The size of the correlated particle emission region is seen to increase significantly with the particle multiplicity of the event.
Date: May 1, 2010
Creator: Khachatryan, Vardan; Sirunyan, Albert M.; Tumasyan, Armen; Adam, Wolfgang; Bergauer, Thomas; Dragicevic, Marko et al.
System: The UNT Digital Library
Single-Sector Supersymmetry Breaking in Supersymmetric QCD (open access)

Single-Sector Supersymmetry Breaking in Supersymmetric QCD

We construct examples of single-sector supersymmetry breaking based on simple deformations of supersymmetric QCD with (weakly) gauged flavor group. These theories are calculable in a weakly coupled Seiberg dual description. In these models, some of the particles in the first two generations of quarks and leptons are composites of the same strong dynamics which leads to dynamical supersymmetry breaking. Such models can explain the hierarchies of Yukawa couplings in the Standard Model, in a way that predictively correlates with the spectrum of SUSY-breaking soft terms.
Date: August 26, 2010
Creator: Franco, Sebastian & Kachru, Shamit
System: The UNT Digital Library
'Dynamical Supersymmetry Breaking, with Flavor' (open access)

'Dynamical Supersymmetry Breaking, with Flavor'

We explore calculable models with low-energy supersymmetry where the flavor hierarchy is generated by quark and lepton compositeness, and where the composites emerge from the same sector that dynamically breaks supersymmetry. The observed pattern of Standard Model fermion masses and mixings is obtained by identifying the various generations with composites of different dimension in the ultraviolet. These 'single-sector' supersymmetry breaking models give rise to various spectra of soft masses which are, in many cases, quite distinct from what is commonly found in models of gauge or gravity mediation. In typical models which satisfy all flavor-changing neutral current constraints, both the first and second generation sparticles have masses of order 20 TeV, while the stop mass is a few TeV. In other cases, all sparticles obtain masses of order a few TeV predominantly from gauge mediation, even though the first two generations are composite.
Date: August 26, 2010
Creator: Craig, Nathaniel; Essig, Rouven; Franco, Sebastian; Kachru, Shamit & Torroba, Gonzalo
System: The UNT Digital Library
Exclusive Production of Ds Ds-, Ds* Ds-, and Ds* Ds*- via e e- Annihilation with Initial-State-Radiation (open access)

Exclusive Production of Ds Ds-, Ds* Ds-, and Ds* Ds*- via e e- Annihilation with Initial-State-Radiation

The authors perform a study of exclusive production of D{sub s}{sup +}D{sub s}{sup -}, D*{sub s}{sup +}D{sub s}{sup -}, and D*{sub s}{sup +}D*{sub s}{sup -} final states in initial-state-radiation events from e{sup +}e{sup -} annihilations at a center-of-mass energy near 10.58 GeV, to search for charmonium 1{sup --} states. The data sample corresponds to an integrated luminosity of 525 fb{sup -1} and was recorded by the BABAR experiment at the PEP-II storage ring. The D{sub s}{sup +} D{sub s}{sup -}, D*{sub s}{sup +}D{sub s}{sup -}, and D*{sub s}{sup +}D*{sub s}{sup -} mass spectra show evidence of the known {psi} resonances. Limits are extracted for the branching ratios of the decays X(4260) {yields} D{sub s}{sup (*)+}D{sub s}{sup (*)-}.
Date: October 27, 2010
Creator: del Amo Sanchez, P.; Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J. et al.
System: The UNT Digital Library
Measurement of CP violation observables and parameters for the decays $B^{\pm}\to DK^{*\pm}$ (open access)

Measurement of CP violation observables and parameters for the decays $B^{\pm}\to DK^{*\pm}$

We study the decay B{sup -} {yields} DK*{sup -} using a sample of 379 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at the PEP-II B-factory. We perform a 'GLW' analysis where the D meson decays into either a CP-even (CP+) eigenstate (K{sup +}K{sup -}, {pi}{sup +}{pi}{sup -}), CP-odd (CP-) eigenstate (K{sub S}{sup 0}{pi}{sup 0}, K{sub S}{sup 0}{phi}, K{sub S}{sup 0}{omega}) or a non-CP state (K{sup -}{pi}{sup +}). We also analyze D meson decays into K{sup +}{pi}{sup -} from a Cabibbo-favored {bar D}{sup 0} decay or doubly suppressed D{sup 0} decay ('ADS' analysis). We measure observables that are sensitive to the CKM angle {gamma}: the partial-rate charge asymmetries A{sub CP{+-}}, the ratios R{sub CP{+-}} of the B-decay branching fractions in CP{+-} and non-CP decay, the ratio R{sub ADS} of the charge-averaged branching fractions, and the charge asymmetry A{sub ADS} of the ADS decays: A{sub CP+} = 0.09 {+-} 0.13 {+-} 0.06, A{sub CP-} = -0.23 {+-} 0.21 {+-} 0.07, R{sub CP+} = 2.17 {+-} 0.35 {+-} 0.09, R{sub CP-} = 1.03 {+-} 0.27 {+-} 0.13, R{sub ADS} = 0.066 {+-} 0.031 {+-} 0.010, and A{sub ADS} = -0.34 {+-} 0.43 {+-} 0.16, where the first …
Date: August 26, 2010
Creator: Aubert, Bernard; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
System: The UNT Digital Library
Flavor Physics in the Quark Sector (open access)

Flavor Physics in the Quark Sector

In the past decade, one of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor. In this time frame, measurements and the theoretical interpretation of their results have advanced tremendously. A much broader understanding of flavor particles has been achieved, apart from their masses and quantum numbers, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. In the past, observations of CP violation were confined to neutral K mesons, but since the early 1990s, a large number of CP-violating processes have been studied in detail in neutral B mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of K,D, and B mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near future, there will be a transition from the current to a new generation of experiments, thus a review of …
Date: August 26, 2010
Creator: Antonelli, Mario; Asner, David Mark; Bauer, Daniel Adams; Becher, Thomas G.; Beneke, M.; Bevan, Adrian John et al.
System: The UNT Digital Library
Search for B-meson decays to b1rho and b1K___ (open access)

Search for B-meson decays to b1rho and b1K___

We present a search for decays of B mesons to final states with a b{sub 1} meson and a {rho} or K*(892) meson. The search is based on a data sample consisting of 465 million B{bar B} pairs collected by the BABAR detector at the SLAC National Accelerator Laboratory. We do not observe any statistically significant signal. The upper limits we set on the branching fractions range from 1.4 to 8.0 x 10{sup -6} at the 90% confidence level (C.L.), including systematic uncertainties.
Date: June 11, 2010
Creator: Aubert, Bernard; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
System: The UNT Digital Library
Search for the B to K nu nu-bar Decay Using Semi-Leptonic Tags (open access)

Search for the B to K nu nu-bar Decay Using Semi-Leptonic Tags

We present an update of the search for the flavor-changing neutral current B{sup +} {yields} K{sup +}{nu}{bar {nu}} decay using 351 X 10{sup 6} B{bar B} pairs collected at the {Upsilon}(4S) resonance with the BABAR detector at the SLAC PEP-II B factory. Due to the presence of two neutrinos in the final state, we require the reconstruction of the companion B in the event through the decay channel B{sup -} {yields} D{sup 0}{ell}{sup -}{bar {nu}}X. We find 38 candidates in the data with an expected background of 31{-+} 12. This allows us to set an upper limit on the branching fraction for B{sup +} {yields} K{sup +}{nu}{bar {nu}} of 4.5 X 10{sup -5} at 90% confidence level.
Date: June 2, 2010
Creator: Aubert, B.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
System: The UNT Digital Library
Hole transport and photoluminescence in Mg-doped InN (open access)

Hole transport and photoluminescence in Mg-doped InN

Hole conductivity and photoluminescence were studied in Mg-doped InN films grown by molecular beam epitaxy. Because surface electron accumulation interferes with carrier type determination by electrical measurements, the nature of the majority carriers in the bulk of the films was determined using thermopower measurements. Mg concentrations in a"window" from ca. 3 x 1017 to 1 x 1019 cm-3 produce hole-conducting, p-type films as evidenced by a positive Seebeck coecient. This conclusion is supported by electrolyte-based capacitance voltage measurements and by changes in the overall mobility observed by Hall effect, both of which are consistent with a change from surface accumulation on an n-type film to surface inversion on a p-type film. The observed Seebeck coefficients are understood in terms of a parallel conduction model with contributions from surface and bulk regions. In partially compensated films with Mg concentrations below the window region, two peaks are observed in photoluminescence at 672 meV and at 603 meV. They are attributed to band-to-band and band-to-acceptor transitions, respectively, and an acceptor binding energy of ~;;70 meV is deduced. In hole-conducting films with Mg concentrations in the window region, no photoluminescence is observed; this is attributed to electron trapping by deep states which are empty …
Date: March 24, 2010
Creator: Miller, N.; Ager, J. W., III; Smith, H. M., III; Mayer, M. A.; Yu, K. M.; Haller, E. E. et al.
System: The UNT Digital Library
Measurement of the 208Pb(52Cr, n)259Sg Excitation Function (open access)

Measurement of the 208Pb(52Cr, n)259Sg Excitation Function

The excitation function for the 208Pb(52Cr, n)259Sg reaction has been measured using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. The maximum cross section of pb is observed at a center-of-target laboratory-frame energy of 253.0 MeV. In total, 25 decay chains originating from 259Sg were observed and the measured decay properties are in good agreement with previous reports. In addition, a partial excitation function for the 208Pb(52Cr, 2n)258Sg reaction was obtained, and an improved 258Sg half-life of ms was calculated by combining all available experimental data.
Date: March 19, 2010
Creator: Folden, C. M., III; Dragojevic, I.; Dullmann, Ch. E.; Eichler, R.; Garcia, M. A.; Gates, J. M. et al.
System: The UNT Digital Library
On the effect of x-ray irradiation on the deformation and fracture behavior of human cortical bone (open access)

On the effect of x-ray irradiation on the deformation and fracture behavior of human cortical bone

In situ mechanical testing coupled with imaging using high-energy synchrotron x-ray diffraction or tomography imaging is gaining in popularity as a technique to investigate micrometer and even sub-micrometer deformation and fracture mechanisms in mineralized tissues, such as bone and teeth. However, the role of the irradiation in affecting the nature and properties of the tissue is not always taken into account. Accordingly, we examine here the effect of x-ray synchrotron-source irradiation on the mechanistic aspects of deformation and fracture in human cortical bone. Specifically, the strength, ductility and fracture resistance (both work-of-fracture and resistance-curve fracture toughness) of human femoral bone in the transverse (breaking) orientation were evaluated following exposures to 0.05, 70, 210 and 630 kGy irradiation. Our results show that the radiation typically used in tomography imaging can have a major and deleterious impact on the strength, post-yield behavior and fracture toughness of cortical bone, with the severity of the effect progressively increasing with higher doses of radiation. Plasticity was essentially suppressed after as little as 70 kGy of radiation; the fracture toughness was decreased by a factor of five after 210 kGy of radiation. Mechanistically, the irradiation was found to alter the salient toughening mechanisms, manifest by the …
Date: January 10, 2010
Creator: Barth, Holly D.; Launey, Maximilien E.; McDowell, Alastair A.; Ager, Joel W., III & Ritchie, Robert O.
System: The UNT Digital Library
B-meson decays to eta' rho, eta' f0, and eta' K* (open access)

B-meson decays to eta' rho, eta' f0, and eta' K*

We present measurements of B-meson decays to the final states {eta}{prime} {rho}, {eta}{prime} f{sub 0}, and {eta}{prime} K*, where K* stands for a vector, scalar, or tensor strange meson. We observe a significant signal or evidence for {eta}{prime} {rho}{sup +} and all the {eta}{prime}K* channels. We also measure, where applicable, the charge asymmetries, finding results consistent with no direct CP violation in all cases. The measurements are performed on a data sample consisting of 467 x 10{sup 6} B{bar B} pairs, collected with the BABAR detector at the PEP-II e{sup +}e{sup -} collider at the SLAC National Accelerator Laboratory. Our results favor the theoretical predictions from perturbative QCD and QCD Factorization and we observe an enhancement of the tensor K*{sub 2} (1430) with respect to the vector K*(892) component.
Date: August 25, 2010
Creator: del Amo Sanchez, P.; Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J. et al.
System: The UNT Digital Library
Observation of the Upsilon(13DJ ) Bottomonium State through Decays to pi+pi-Upsilon(1S) (open access)

Observation of the Upsilon(13DJ ) Bottomonium State through Decays to pi+pi-Upsilon(1S)

Based on 122X10{sup 6} {upsilon}(3S) events collected with the BABAR detector, we have observed the {upsilon}(1{sup 3}D{sub J}) bottomonium state through the {upsilon}(3S){yields}{gamma}{gamma}{upsilon}(1{sup 3}D{sub J}){yields}{gamma}{gamma}{pi}{sub +}{pi}{sub -}{upsilon}(1S) decay chain. The significance is 6.2 standard deviations including systematic uncertainties. The mass of the J = 2 member of the {upsilon}(1{sup 3}D{sub J}) triplet is determined to be 10164.5{-+}0.8 (stat.) {-+} 0.5 (syst.) MeV/c{sup 2}. We use the {pi}{sup +}{pi}{sup -} invariant mass and decay angular distributions to confirm the consistency of the observed state with the orbital angular momentum and parity assignments of the {upsilon}(1{sup 3}D{sub J}).
Date: June 2, 2010
Creator: del Amo Sanchez, P.; Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J. et al.
System: The UNT Digital Library
Search for fj(2220) in radiative J/psi decays (open access)

Search for fj(2220) in radiative J/psi decays

We present a search for f{sub J}(2220) production in radiative J/{psi} {yields} {gamma}f{sub J}(2220) decays using 460 fb{sup -1} of data collected with the BABAR detector at the SLAC PEP-II e{sup +}e{sup -} collider. The f{sub J}(2220) is searched for in the decays to K{sup +}K{sup -} and K{sub S}{sup 0}K{sub S}{sup 0}. No evidence of this resonance is observed, and 90% confidence level upper limits on the product of the branching fractions for J/{psi} {yields} {gamma}f{sub J}(2220) and f{sub J}(2220) {yields} K{sup +}K{sup -}(K{sub S}{sup 0}K{sub S}{sup 0}) as a function of spin and helicity are set at the level of 10{sup -5}, below the central values reported by the Mark III experiment.
Date: July 30, 2010
Creator: del Amo Sanchez, P.; Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J. et al.
System: The UNT Digital Library
Pu2O3 and the plutonium hydriding process (open access)

Pu2O3 and the plutonium hydriding process

None
Date: August 4, 2010
Creator: Dinh, L. N.; Haschke, J. M.; Saw, C. K.; Allen, P. G. & McLean, W., II
System: The UNT Digital Library